unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Timer1: TTimer;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}
{
BOOL SystemParametersInfo(
  UINT uiAction, // system parameter to query or set
  UINT uiParam,  // depends on action to be taken
  PVOID pvParam, // depends on action to be taken
  UINT fWinIni   // user profile update flag
);

Windows NT 5.0 and later, Windows 98: Determines whether
 a screen saver is currently running on the window station
 of the calling process. The pvParam parameter must point to
 a BOOL variable that receives TRUE if a screen saver is
 currently running, or FALSE otherwise. Note that only the
 interactive window station, "WinSta0", can have a screen saver
 running.
}
procedure TForm1.Button1Click(Sender: TObject);
var
  b:integer;
begin
  b:=0;
  SystemParametersInfo(SPI_GETSCREENSAVERRUNNING,0,@b,0);
  memo1.lines.add(inttostr(b));
  if b<>0 then
    showmessage(inttostr(b));
end;

end.